The intensive use of antibiotics has exerted a selective evolutionary pressure on micro-organisms to produce genetically based resistance mechanisms. Modern medicine and socio-economic behaviour exacerbates the problem of resistance development by creating slow growth situations for pathogenic microbes, e.g. in artificial joints, and by supporting long-term host reservoirs, e.g. in immuno-compromised patients.
In hospital settings, an increasing number of strains of Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus spp., and Pseudomonas aeruginosa, major sources of infections, are becoming multi-drug resistant and therefore difficult if not impossible to treat:                S. aureus is resistant to β-lactams, quinolones and now even to vancomycin;        S. pneumoniae is becoming resistant to penicillin or quinolone antibiotics and even to new macrolides;        Enteroccocci are quinolone and vancomycin resistant and β-lactam antibiotics are inefficacious against these strains;        Enterobacteriacea are cephalosporin and quinolone resistant;        P. aeruginosa are β-lactam and quinolone resistant.        
Further new emerging organisms like Acinetobacter spp., Burkholderia spp. Stenotrophomonas maltophilia, or Clostridium difficile, which have been selected during therapy with the currently used antibiotics, are becoming a real problem in hospital settings.
In addition, microorganisms that are causing persistent infections are increasingly being recognized as causative agents or cofactors of severe chronic diseases like peptic ulcers or heart diseases.
Certain heterocyclic compounds containing a 2-(aminomethyl)-morpholin-4-ylethyl -derived moiety are known as antibacterial agents from WO 2004/035569, WO 2006/014580, WO 2006/021448 and WO 2008/006648.
Certain heterocyclic compounds containing a 3-(aminomethyl)-pyrrolidin-1-ylethyl -derived moiety are known as antibacterial agents from WO 2006/002047 and WO 2008/006648.
Certain heterocyclic compounds containing a 3-(aminomethyl)-piperidin-1-ylethyl -derived moiety are known as antibacterial agents from WO 2004/035569, WO 2006/014580 and WO 2006/021448.
Certain heterocyclic compounds containing a 4-amino-piperidin-1-ylethyl-derived moiety are known as antibacterial agents from WO 01/07432, WO 01/07433, WO 02/08224, WO 02/24684, WO 02/056882, WO 2003/064421, WO 2004/002490, WO 2004/058144, WO 2006/046552, WO 2006/134378, WO 2007/042325 WO 2007/118130 and WO 2008/006648.
Certain heterocyclic compounds containing a 8-ethyl-8-aza-bicyclo[3.2.1]oct-3-ylamino-derived moiety are known as antibacterial agents from WO 2004/035569 and WO 2006/021448.
Moreover, certain heterocyclic compounds containing a 3-ethyl-3-aza-bicyclo[3.1.0]hex-6-ylamino-derived moiety are known as antibacterial agents from WO 2006/010040 and WO 2006/032466.
Various embodiments of the invention are presented hereafter.